(1) Field of the Invention
The present invention relates to transgenic potato plants (Solanum tuberosum) which are lepidopteran insect resistant. In particular, the present invention relates to potato plants containing multiple repeating segments of DNA which encode an endotoxin from Bacillus thuringiensis so that the potato plant is provided with the insect resistance.
(2) Prior Art
It is well known that the bacterium Bacillus thuringiensis (B.t.) produces proteinaceous parasporal inclusions during sporulation. These Bacillus thuringiensis proteins are toxic and highly specific to certain lepidopteran, coleopteran, and dipteran insects (Hofte, H. and H. R. Whiteley, Microbiological Reviews, 53, 242-255 (1989)). Crystal and spore preparations from B. thuringiensis var. kurstaki (B.t.k.) have been used for many years as insecticides to control a variety of lepidopteran insects (Dulmage, H. T., Microbial Control of Pest and Plant Diseases 1970-1980 in: H. D. Burges (ed), Academic, London, pp. 193-222 (1980)). The protoxin from Bacillus thuringiensis var. kurstaki has a size of 130 kD, which is converted to a biologically active polypeptide of 68 kD in the midgut of susceptible insects (Bulla, L. A., Jr., et al., Biochem. Bio Phys. Res. Commun. 91, 1123-1130 (1979); and Adang, M. J., et al., Gene, 36, 289-300 (1985)).
Because Bacillus thuringiensis proteins have short half-lives when applied topically (Beegle, C. C., et al., Environ. Entomol., 10, 400-401 (1981)), introduction of Bacillus thuringiensis genes into plants could be a better utilization of this biological pest control system. Transgenic tobacco, tomato, and cotton plants containing Bacillus thuringiensis var. kurstaki genes have been reported to be resistant to attacks from target lepidopteran insects (Perlak, F. J., et al., Bio/technology 8, 939-943 (1990); Barton, K. A., et al., Plant Physiol. 85, 1103-1109 (1987); Vaeck, M., et al., Nature, 328, 33-37 (1987); and Delannay, X., et al., Bio/Technology, 7, 1265-1269 (1989)). Hornworm has been found to be susceptible to the Bacillus thuringiensis var. kurstaki encoded toxin in tobacco (MacIntosh, S. C., et al., J. Invertebrate Pathology, 56, 258-266 (1990)).
The problem is to provide the DNA encoding the protein in potatoes such that a sufficient amount is encoded in the plant to make it resistant to the lepidopteran insects. This has not been accomplished by the prior art.